Question

An automobile cooling system holds 18 L of water. How much heat does it absorb if its temperature rises from 15 ℃ to 95 ℃?

Answer 1

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Q = mc(Tf - Ti)

where

Q = heat

m = mass of the substance

Tf = Final temperature

Ti = initial Temperature

Given:

Tf = 90 degree C

Ti = 20 degree C

c = specific heat of water is 4190 J/kg K

Volume = 18 Liters

since we know that density of water is 1000 kg/m^3

and

density = mass/volume

lets first convert Liters to cubic meters

simple relations:

1 L = 1000 ml

1ml = 1cubic cm

1 cubic meters = 1000000 cubic cm

lets convert;

18Liters(1000 cubic cm / 1 Liters) (1 cubic meter / 1000000 cubic cm )

= 0.018 cubic meter (volume)

using the density of water

mass = density x volume

= (1000 kg / cubic meter)(0.018 cubic meter)

= 18 kg of water

then,

Q = 18kg( 4190 J/kg K) (70 K)

= 5279400 J of heat.

Hope it helps you.